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"Heil Hitler"....how can these two words help in breaking the most sophisticated machine of that time in The Imitation Game (2014)?

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    Numberphile has a great two-part video series on this topic: 1.) youtube.com/watch?v=G2_Q9FoD-oQ 2.) youtu.be/V4V2bpZlqx8 – Lil' Bits Mar 11 at 18:48
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    For the record, the movie is wildly inaccurate on practically the entire story. He didn't invent that machine, there was far more than one of them, everybody knew about cribs and they were already using them and didn't need some bar floozy to teach them about it, he wasn't intellectually crippled by his chemical castration, etc. I did like the movie, but it's more fiction than non-fiction. – zibadawa timmy Mar 11 at 21:00
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    You can find a detailed explanation of how Turing's machine worked here. – DarthFennec Mar 11 at 23:53
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    He also not anywhere near as socially awkward as depicted, as he had enough social ability to conduct numerous same-sex affairs while that was illegal and could have been career-ending blackmail material for someone with access to highly classified material. But "socially awkward genius" is now a trope, and one that Cumberbatch has built his career on, so... – Ross Thompson Mar 13 at 15:13
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    Agreed with @zibadawatimmy - this film is not one to watch for historical accuracy. Almost everything in it is wrong. The 'heil hitler' crib wasn't even useful in breaking the navy enigma, which is what Turing's team in Hut 8 were almost exclusively working on. The film also depicts the breaking of Enigma as a thing that happened at a single point in time, before which it was not read and after which it was - this is also completely wrong. Enigma was being read throughout the war - what changed was how quickly it could be decoded and how quickly the British could react to changes in the code. – J... Mar 13 at 18:07
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The actual decryption was very complex but Bletchley Park was given a BIG clue because...

To aid this process, all Turing needed was a word (or a group of words) that he was positive the Germans would use in each of their Enigma-encrypted messages. What was that word, or rather, that phrase?

‘Heil Hitler’

Germans put the phrase ‘Heil Hitler’ at the end of every encrypted message. This seemingly small mistake eventually contributed to their ultimate defeat.

Read more at the Source

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    Another example - the allies knew the first message of the day was usually a weather report, and they knew what the weather was, so could look for matches of e.g. "Regen" or "17 Grad Celsius" in those in order to get the key for the day. – OrangeDog Mar 11 at 17:28
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    It's called "crib". Another reliable crib was word "eins" (one), so the cryptographers created so called "eins catalogue", similar to today rainbow tables ;-) – Edheldil Mar 11 at 17:49
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    The limitation that allowed the Allies to break the Enigma was that any letter on the Enigma keyboard typed would never result in that letter as being an output. You could never press 'a' and get 'a'. This, and knowledge of the contents (usually called a "known plaintext attack"), allowed the Allies to brute force attack ciphertexts. – Naftuli Kay Mar 11 at 18:47
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    @NaftuliKay that seems more like a complete answer than a comment – Aethenosity Mar 12 at 1:24
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    Also heard that one German, supposedly in a quite outpost, send something like: "I have nothing to report" everyday which helped break the enigma code. – user2121 Mar 12 at 11:32

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